Another factor that should be taken into account is that two nuclei
may undergo mutual Coulomb excitation and emit neutrons [1]}.
To consider such effects, we need to introduce an extra factor \(\mathcal {P}^{2}(b_{T})\) 
in the calculation of the cross section, where \(\mathcal {P}(b_{T})\) 
is the probability of emitting a single neutron from an excited nucleus
and can be parametrized as [2]},
\(\mathcal {P}(b_{T})=\sum _{N_{\gamma }=1}^{\infty }\frac{1}{N_{\gamma }!}w^{N_{\gamma }}e^{-w}=1-\exp (-w),\) 
